用于原油交接计量的密度计选型时，要考虑防爆级别应符合（）防爆等级这一要求。
A.现场
B.规定
C.标准
D.二级
参考答案：A
Which of the following is a difference between an on-the-run and an off-the-run issue An on- the-run issue:（）
A. is the most recently issued security of that type.
B. tends to sell at a lower price.
C. has a shorter maturity than an off-the-run issue.
以物流成本的不同项目作为物流成本的控制对象，可以将物流成本划分为（）。
A．材料费
B．人工费
C．燃油费
D．差旅费
E．办公费
